The present invention relates to electrode materials for the electrochemical synthesis of germane (GeH4). Several electrode materials have been previously reported in literature, which include Ni, Cu, Pb, Sn, Cd, Zn, Pt, Al, Ge, Graphite, Fe and Hg.
SU1732697A1, RU2071993 and RU2230830 taught the use of a Ni electrode to electrochemically generate germane with current efficiencies estimated at 15-20% when operating at optimal conditions in a flow-through cell with cross mixing of anolyte and catholyte. The patents focused on the process of cross-mixing the anode and cathode electrolytes and not on, the electrode material itself.
U.S. Pat. No. 5,158,656 alleged the use of a germanium electrode to generate germane at current efficiencies of 30%. However, this result is in contrast to that reported in a journal publication (Green et. al., J. Electrochem. Soc., v106, n3, p253) which showed that germanium electrodes do not generate germane efficiently.
Djurkovic et. al. (Glanik Hem. Drustva, Beograd, v25/26 (8-10), 1961, p469) studied several different metals (Al, Fe, Pb, Cu, Zn and Hg) as electrodes.
Tomilov et. al. (Inorganic Materials, 2008, v44, n10, p1081) evaluated several different metals as electrodes in a filter-press electrolyzer with the catholyte circulated by a centrifugal pump and concluded that copper and cadmium were optimal electrode materials with current efficiencies of 32-34%. The authors' also reported that the current efficiencies decreased over a period of time due to the deposition of Germanium on the electrode surface.
Thus, there is still a need in the art to provide effective means for the electrochemical synthesis of germane, especially, with stable performance.